Systemic lupus erythematosus (SLE) is an autoimmne disease that is characterized primarily by the presence of antibodies against nuclear components. However, about 10-20% of the patients with SLE synthesize antibodies against three ribosomal proteins called P0, P1, and P2. It has been shown that these three proteins contain a common epitope that is recognized by the SLE patients' antibodies. proteins P1 and P2 are thought to be highly conserved in nature and sequencing studies of those proteins isolated from Artemia salina show that the carboxyl terminal 22 amino acids of both proteins are identical. There is no homology, however between the amino terminal residues of these proteins.
There is, thus, a need for a reliable and sensitive method of detecting those SLE patients who do not produce antibodies against nuclear components. The present invention is directed to a method of detecting those SLE patients who produce antibodies against ribosomal proteins rather than nuclear components. The method of the invention is, thus, complimentary to existing assays and enables clinicians to detect SLE patients who would not heretofor been detected by existing diagnostic assays.